Sanitary napkin with improved wrap material

ABSTRACT

A sanitary napkin having a conventional central pad of absorbent material, and an improved wrap material disposed around the central pad and comprising a high-loft, nonwoven fabric having a discontinuous backing layer of flexible adhesive. The fabric includes a multiplicity of hydrophobic fibers individually looped outwardly from the backing layer with the ends of each loop embedded in the backing layer.

ilnited States Patent Skora [451 May 30,1972

[54] SANITARY NAPKIN WITH IMPROVED WRAP MATERIAL [72] Inventor: RobertF. Skora, Neenah, Wis.

[73] Assignee: Kimberly-Clark Corporation, Neenah,

I Wis. V

[22] Filed: Nov. 20, 1969 [21] Appl. No.: 878,393

[52] US. Cl. ..l28/290, 161/148 [51] Int. Cl. ..A6lf 13/16 [58] Field ofSearch... .....128/284, 287, 288, 290, 296;

[56] References Cited UNITED STATES PATENTS Johnson ..128/290 W Morin128/284 Bletzineer et a1. 128/290 Primary ExaminerCharles F. RosenbaumAttorney-Wolfe, Hubbard, Leydig, Voit & Osann, Ltd.

[57] ABSTRACT A sanitary napkin having a conventional central pad ofabsorbent material, and an improved wrap material disposed around thecentral pad and comprising a high-loft, nonwoven fabric having adiscontinuous backing layer of flexible adhesive. The fabric includes amultiplicity of hydrophobic fibers individually looped outwardly fromthe backing layer with the ends of each loop embedded in the backinglayer.

9 Claims, 13 Drawing Figures Patented May 30, 1972 3 Sheets-Sheet lPatented May 30, 1972 3,665,922

3 Sheets-Sheet 2 424m! amawym/ Fga Wra /11:

Patented May 30, 1972 3,665,922

3 Sheets-Sheet SANITARY NAPKIN WITH IMPROVED MATERIAL The presentinvention relates generally to sanitary napkins and, more particularly,to a sanitary napkin having an improved wrap material.

It is a primary object of the present invention to provide a sanitarynapkin having improved ability to absorb and retain menstrual exudate.

It is another object of the invention to provide an improved sanitarynapkin of the type described above which provides extremely rapidabsorption of menstrual exudate.

A further object of the invention is to provide an improved sanitarynapkin of the foregoing type which is soft and comfortable to the user.

Yet another object of the invention is to provide such an improvedsanitary napkin which minimizes retention of menstrual exudate in thewrap material.

Other objects and advantages of the invention will be apparent from thefollowing detailed description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of a sanitary napkin embodying theinvention, with fragments thereof broken away to reveal the internalstructure; I

FIG. 2 is a section taken along line 2--2 in FIG. 1;

FIG. 3 is an enlarged fragmentary perspective view of one of theinternal elements in the napkin of FIGS. 1 and 2;

FIG. 4 is a schematic side elevation of one form of apparatus which maybe used to produce the improved wrap material included in the napkin ofFIGS. 1 and 2;

FIG. 5 is a fragmentary plan view somewhat simplified and exaggeratedfor the sake of clarity of illustration, of an illustrative web of basematerial prepared by the apparatus of FIG. 4 with portions of thematerial broken away to expose the various layers;

FIG. 6 is a fragmentary plan view of the wrap material employed in thenapkin of FIGS. 1 and 2, with portions broken away to expose the variouslayers;

FIG. 7 is an enlarged, simplified and somewhat exaggerated section takenalong section line 7-7 in FIG. 6;

FIG. 8 is an enlarged, simplified and somewhat exaggerated section takenalong line 8-8 in FIG. 6;

FIG. 9 is an enlarged schematic detail in side elevation of the formingdrum and gathering blade of the apparatus shown in FIG. 4;

FIG. 10 is a further enlarged schematic side elevation illus trating insomewhat idealized fashion the sequence of gathering and looping ofindividual fibers;

FIG. 11 is an enlarged schematic fragmentary view taken along the lines11-11 of FIG. 10 showing a fragment of the fiber web and adhesivepattern with illustrative fibers attached to the adhesive;

FIG. 12 is a simplified schematic view taken along the lines 12-12 ofstill another sequence as shown in FIG. 10', and

FIG. 13 is an enlarged schematic bottom view showing the sequence of thepartial consolidation or closing of the open adhesive pattern to form adiscontinuous adhesive backing.

While the invention will be described in connection with certainpreferred embodiments, it will be understood that it is not intended tolimit the invention to these particular embodiments. On the contrary, itis intended to cover all alternative, modifications, and equivalentarrangements as may be included within the spirit and scope of theinvention.

In sanitary napkin construction, it is desirable to have an absorbentstructure which (1) immediately accepts body exudate, (2) rapidlytransports the exudate away from the discharge source, and (3)efiectively contains the exudate within the confines of the napkin, allwhile the top surface of the napkin is maintained relatively dry. Inaddition, the absorbed exudate should not be allowed to spread to thesides of the napkin, run over the top edges of the napkin, or soakthrough the bottom of the napkin, especially if the absorptive capacityof the napkin has not been reached.

Turning now to the drawings, and referring first to FIGS. 1 and 2, thereis shown a sanitary napkin 10 having a main absorbent core 11 of fluidabsorbent material, a fluid control element l2, and a fluid perviouswrapper 13 enclosing the absorbent elements and overlapped in a knownmanner, and providing end tabs for fastening purposes. The absorbentcore 11 may be of varying construction, including top and bottom layerscomprising multiple plies of cellulose wadding 14 and a central pad ofwood fluff 15. Alternatively, the core 11 may be all fluff. Other knownabsorbent materials such as batts of cotton and/or various types ofsynthetic fibers may also be used for the main body portion. The mainbody portion, in itself being of conventional construction, acts only asa cooperating part of the present invention, the important requisitebeing that the core be lower in density and consequently have largerinterstices than the central element 12.

Other parts of the illustrative pad construction are also known, such asthe fluid impervious baffle 16 of plastic film or the like which isoften employed to inhibit strike through, and sidestrips 17, such aswaxed tissue, or water-resistant film,

' may be employed to inhibit inadvertent side staining caused bymigration of exudate to side edges of the pad. If desired, a secondcontrol element 18 may be provided on the opposite side of the pad fromthe control element 12 mentioned previously.

The particular control element 12 employed in the illustrativeembodiment shown most clearly in FIG. 3, is described in more detail inUS. Pat. No. 3,375,827, assigned to the assignee of the presentinvention. The control element 25 preferably has an embossed patterndefining various degrees of compression, so that it has a significantlyhigher average of density and smaller pores than the interior coreelements 14 and 15 which make up the main absorbent pad 1 1.

In accordance with the present invention, the sanitary napkin isprovided with an improved wrap material comprising a high-loft, nonwovenfabric, having a discontinuous backing layer of flexible adhesivedisposed adjacent the central pad, and a multiplicity of fibersindividually looped outwardly from said backing layer with the ends ofeach loop embedded in the backing layer. Thus, in the illustrativeembodiment, the wrapper material 13 is a high-loft, nonwoven materialpreferably prepared by the method and apparatus illustrated in FIG. 4.This apparatus includes a web forming section 20 and an adhesivecompacting and fiber looping section 30. The web forming section 20 isgenerally similar to the apparatus disclosed in copending applicationsSer. No. 498,929 and Ser. No. 553,483.

Multiple slivers 21 of heat-settable textile fibers are drawn from theirrespective supply cans (not shown) into a draw frame 22 which comprisesa series of pairs of grooved rolls 23, the rolls of each pair beingdriven by appropriate gearing well known in the art, at a peripheralrate of speed slightly faster than the rate of operation of thepreceding pair. As the juxtaposed slivers pass through draw frame 22,the individual fibers are drafted and spread out to form a flat striatedweb of substantially alined fibers as shown at 24. Web 24 is maintainedon a supporting conveyor sheet 25 on the surface of which a patternedadhesive has been previously applied.

In the illustrative arrangement the conveyor sheet 15 comprises anendless conveyor belt treated on at least its upper surface with arelease agent, e.g., a woven glass fiber with a surface coating oftetrafluoroethylene resin. Other release coatings are well known, andcomprise such materials as silicone, fatty acid metal complexes, certainacrylic polymers, and the like. Heat resistant films or thin metalsheets treated with release agents may also be used as the carriersheet.

Prior to the time the web 24 is picked up by the belt 25, the latter hasimprinted on its release-treated surface a pattern of flexiblethermoplastic adhesive such as is shown at 26 in FIG. 5. It isunderstood that the adhesive is actually on the underside of belt 25which becomes the upper surface after passing around roll 27 whereby theadhesive pattern 26 directly contacts the fiber web 24. The pattern isshown as being visible in FIG. 5 only for illustrative purposes.

The belt 25 is fed around roll 27 at a speed slightly in excess of thedelivery speed of the final pair of rolls 23 in order to maintain web 24under slight tension whereby the individual highly-drafted fibers areretained in their alined and tensioned condition. Drive rolls 28, 29 arerotated to drive belt 25 at a speed sufficient to maintain the propertension on the web 24.

In the method shown for applying adhesive, the belt 25 is fed through anip formed between a printing roll 30 and a backup roll 31 maintained invery light pressure engagement therewith. The surface of printing roll30 is provided with an intaglio pattern which picks up adhesive 32 fromdip pan 33. Part of the adhesive thus picked up is removed by a doctorblade 34 leaving only the intaglio patterned surface filled. Theprinting roll 30 then transfers this metered amount of adhesive in apreselected pattern to the underside of release coated belt 25. Thepattern shown in FIG. is in the form of an open diamond pattern ofadhesive.

Since the surface of belt 25 is treated with a release coating, theadhesive remains substantially on the surface with no penetrationtherein and is preferably in a somewhat tacky condition. The printedbelt is drawn from the printing nip around roll 27 positioned closelyadjacent the output end of draw frame 22, and, as stated above, at aspeed slightly in excess of the delivery speed of the last two rolls inthe draw frame. The web 24 emerging from the draw frame 22 is depositedon the tacky adhesive on belt 25 and held in tensioned engagementtherewith by the adhesive and the above-mentioned speed differential.This continuous tension prevents the fibers in the web from losing theirhighly drafted and alined condition.

If desired, additional alined and highly drafted fibers may be added tothe web 24 on the adhesively printed belt 25. For this purpose a seconddraw frame 35 similar to the draw frame 22 is provided to drawadditional slivers 36 of fibers from their supply cans (not shown) and,after drafting and alining them, deposit the fibers on the moving web 24carried by the belt 25. In such cases, the amount of adhesive printed onthe belt 25 is increased so that some penetrations of the adhesivepattern reach the fibers from the second draw frame 35, and togetherwith the speed differential of the belt 25 relative to the last pair ofrolls in the draw frame 35, maintains these fibers under slight tensionwhereby they also maintain their highly drafted and alined condition.

An example of the web 24 formed by the apparatus is shown in FIG. 5. Aspreviously mentioned, a series of parallel and diagonally disposed linesof adhesive are printed in crisscross fashion on the belt to formpattern 26 of adhesive having substantial open spaces in theconfiguration of diamonds. It should be appreciated, of course, thatFIG. 5 is only intended to be illustrativ and, while the linesrepresenting the fibers for both components 24a and 24b are spaced apartfor clarity, in practice the highly drafted fibers of both componentsare very close to one another. Following deposit of web components 240and 2412 on the adhesive printed belt 25, the belt is drawn around aheated drum 39 where fusing and curing of the adhesive is substantiallycompleted while the web 24 is maintained in firm contact therewith tobond the individual fibers. To insure effective heating and fusing ofthe adhesive, it is desirable that travel of the combined belt and webbe around a substantial portion of the drum 39. In the illustratedembodiment, a fly roll 39 a is disposed to provide wrap for the combinedbelt and web as they travel around the drum 39 to insure completeembedment of the fibers in the adhesive. The fibers of the web 24 arethus bonded together while retaining their highly drafted andsubstantially alined condition in the particular pattern in which theywere deposited on the open pattern of adhesive 26 printed on the belt25.

After leaving the fly roll 39a, the combined web 24 and belt 25 arepreferably passed over the drive roll 29 which also serves as a coolingdrum, to set the adhesive. The bonded web 24 is stripped from therelease coated surface of the belt 25 by the guide roll 41 as the webleaves the cooling roll 29.

In general, any of the various known adhesives may be employed. Itshould, however, be appreciated that the particular adhesive used isdependent upon the characteristics of the flexible heat-settable fibrousweb that is being employed, i.e. the adhesive should be reactivatableand softened in the heat-setting range of the particular fibrousmaterial being used. In addition, the adhesives should also: beapplicable to the base web 24 by procedures which will not disarrangethe fibrous structure of the web; be reactivatable in the subsequentadhesive gathering and partial consolidation stage of the process; andform a flexible discontinuous backing layer for the finished fabric andshould strongly bond the fiber loops in place.

While various well-known adhesives may be employed in the foregoingprocess, advantages reside in the use of plastisols, which are colloidaldispersions of synthetic resins in a suitable organic ester plasticizer,and which under the influence of heat provide good binding power whileremaining soft and flexible. While many adhesives of this type areknown, those found particularly useful for incorporation in the productof this invention include vinyl chloride polymers, and copolymers ofvinyl chloride with other vinyl resins, plasticized by organicphthalates, sebacates, or adipates. These provide a fast curingplastisol adhesive characterized by relatively low viscosity, lowmigration tendencies, and minimium volatility. Such adhesives remainsoft and flexible after curing, and can be reactivated by subsequentheating.

It has been found that other adhesive systems may be employed in theprocess, such as organisols, utilizing resins such as the vinyl chloridepolymers, and copolymers. Furthermore, other adhesives may be employedprovided that they satisfy specified characteristics in the base webproduced in the web forming stage, and in the finished fabric producedin the adhesive compacting and fiber looping stage. For example,emulsions of thermoplastic resins such as acrylics and rubber-likecompounds, illustratively ABS, have the requisite properties to serve asthe bonding adhesive for the web 24.

The base material made as heretofore described and comprising a web ofhighly-drafted, heat-settable, fibers embedded in an open adhesivepattern, is then fed into the adhesive consolidating and fiber loopingsection 40 of the system shown in FIG. 4. The web 24 while still undertension is fed around an idler roll 42 and onto the surface of a heatedforming drum 47. The forming drum is maintained at a temperature whichwill soften the adhesive to a tacky state so that it adheres to the drumsurface while also heating the fibers sufficiently to bring them intotheir heat-setting range. In its preferred embodiment the drum 47 ismade of metal with a highly polished chromium plated surface which isinternally heated. Also, the web 24 is desirably arranged to travel asubstantial distance around the drum 47 (i.e. have a relatively highdegree of wrap) with the open pattern of adhesive 26 in contact with theheated drum surface to provide adequate residence time.

As the web 24 is fed onto the drum 47 the heat from the drum surfaceheats the fibers to their heat-setting temperature range and reactivatesand softens the adhesive printed on the underside of the web, causing itto become tacky and to adhere slightly to the drum surface therebymaintaining the web under constant tension. The drum temperature shouldbe maintained below the melting point of the adhesive to preventdispersion of the adhesive into the fibers of the web and to minimizebonding of the adhesive lines as will hereinafter be described ingreater detail. The web of fibers and softened adhesive is reformed bythe cooperative action of the drum 47 and a gathering blade 48 having aflat edge 49. The blade edge 49 operates to consolidate the openadhesive pattern 26 into a backing layer of adhesive whilesimultaneously looping the fibers of the web outwardly from the openspaces in the original adhesive pattern. The reformed and consolidatedmaterial 50 then leaves the blade edge 49 and onto a flat takeoffsurface 51 and a discharge conveyor 52.

The speed at which the material leaves the gathering blade is closelycoordinated with the surface speed of the drum to heat set the fibers intheir looped positions while rendering the adhesive non-tacky so theconsolidation of the adhesive will only be partial and the bonding oftransverse lines of adhesive minimized. To this end and as shown in FIG.4, this may be accomplished by maintaining the take-off surface 51 atthe ambient temperature or slightly higher by directing an air spray 53at the bottom surface of take-off member 51. While this providesadequate cooling to carry out the objectives of the conditioning step,other means such as a water spray or a refrigerated fluid could beemployed to provide a lower temperature if desired. Indeed, as long asthe fluid is inert as regards the fibers and adhesives, application maybe directly on the partially consolidated and reformed web. Thetake-away speed should then be set so that, at the temperature of thetake-away surface, the fibers will be heat set and yet the bonding ofmerging lines of adhesive will be minimized. In this connection, itshould be noted that the the adhesive should be maintained below itsmelting point to minimize the flowing together of the merging adhesivelines which would provide undesired bonds.

Turning now to FIGS. through 13, the method of making the elastic,high-loft, nonwoven fabric 50 will be explained in greater detail inconnection with an illustrative sequence of the gathering and looping ofsingle fibers of the web 24 (FIGS. 10 through 12) and the partialconsolidation of the illustrative diamond adhesive pattern 26 (FIG. 13).As seen in FIG. 11, the fiber has a portion P which extends across theopen space of the diamond pattern of adhesive 26 from point A to B whereit is embedded in the adhesive. Referring to FIG. 10, the series ofviews in this Figure illustrates how the portion P of the fiber isformed into a loop; when point A being carried around the heated drum 47impinges against the gathering blade edge 49, its forward motion ishalted and it is scraped along the surface of the drum. Point Bcontinues to advance with the drum surface since due to its softened andtacky condition it adheres to the the smooth drum surface.

As point B advances relative to point A, the portion P of the fiberbetween points A and B is caused to bow outwardly from the drum surface.Finally, point B overtakes point A and these points of adhesive arebrought close together without being consolidated as seen in FIG. 12. Inthe meantime, fiber portion P has been looped outwardly from the drumsurface. While this is occurring, of course, additional adhesive pointsC-D, etc., travelling around the drum 47 impinge against the gatheringblade edge 49 causing a consolidation of these adhesive points andlooping of their intermediate fiber portions P as is also indicated inFIG. 12. This occurs simultaneously at all points across the web at theblade edge producing a backing layer of adhesive from which extends themultiplicity of loops formed by the fibers of the base web. The layer ofadhesive is carried away from the blade edge along the take-off surface51 and provides a backing layer for the outwardly looped fibers, thusproducing the fabric 50.

Also, not only does each fiber portion P loop outwardly from the drumsurface but as the loop is formed it may twist or turn. The degree ofloop twisting, and indeed, whether any twisting occurs, is dependentupon such factors as the degree of adhesive consolidation, fiberstiffness, blade angle (as hereinafter defined) and relative uniformityof loop size. In a particular situation, the formed loops may turnthrough an angle of up to 180.

FIG. 13 illustrates the partial consolidation that is desired when theopen adhesive pattern is the exemplary diamond pattern. Thus,considering a single diamond S, each of the four comers T represents thecrossing point of two intersecting lines of adhesive U and V. At everycorner T then, as the adhesive is scraped along the surface of the drum,the crossing adhesive lines U and V are brought closer and closertogether. The points closest to the corners T merge first because of theshorter distance of separation. Accordingly, point P on line U willmerge with point P on line V before point P will meet point P Similarly,on the other side of the comer, the closer set of points (e.g. P andP,,) will merge before points P and P To provide the desired wrapmaterial for use in the present invention, the take-away speed ismaintained at a rate such that the adhesive diamonds are not completelyconsolidated but are collapsed into fiat hexagonal shapes in which thecrossing points of adhesive have been transformed by partialconsolidation of the adhesive into lines that form the sides of thehighly elongated hexagons, as shown in FIG. 13. The closed, compact formof the nonwoven fabric may be stretched apart to break the bonds ofminimal strength (i.e. the bonds that will break before adhesive ruptureor other degradation of the product). The fabric is then allowed torelax to come to an equilibrium state in its drawn or open position.

The drawing may be accomplished by hand and can be achieved by pullingthe fabric apart (i.e. along the machine direction). As shown in FIG. 4,the fabric exit end of the conveyor 52 may be provided with a roll 54 tofon'n a nip and a pair of rolls 55, also forming a nip. Drawing isaccomplished by driving the rollers 55 at a higher speed.

With respect to the loops, it should be appreciated that the heights ofthe fiber loops throughout the fabric vary according to the spacingbetween the points of attachment of each fiber to the open adhesivepattern in the base web. Referring to FIGS. 8, l1, and 12, it will beseen, for example, that the loop formed by the fiber portion P, betweenthe points of adhesive attachment CD will have a lower height than theloop formed by the longer fiber portion P between the points A,B. Thisresults in a dense fabric with the lower loops supporting and fillingaround the higher loops and the top surface of the fabric being formedby the tops of the higher loops.

In accordance with an important aspect of this invention, the base webused to form the high-loft wrap material comprises fine denier,heat-settable, hydrophobic fibers. The fine denier of the fibersprovides desired softness to the fabric, the heat settablecharacteristic improves the loft or bulk stability of the fabric, andthe hydrophobic nature of the fibers provides a wrap material which issubstantially non-wetting, while at the same time readily passingmenstrual fluids therethrough. The denier of the fibers is preferably inthe range of from about 1.5 to about 3.0 denier. Suitable hydrophobicproperties are provided by fibers of polyester, polypropylene, oracrylic. By heat-settable it is meant that the material will maintainthe looped configuration into which it has been formed in accordancewith the present invention, regardless of whether the stability of theloop may be attributed to what is technically considered heat setting orwhether the setting is the result of some other phenomena.Representative examples of suitable materials include any of thecommercially available acrylic fibers such as, for example, Creslon"(American Cyanamide, Stamford Conn.) and Orlon (E.l. du Pont de Nemoursand Company, Wilmington, Del.) and olefins such as polypropylene. Ifdesired, a blend of fibers may be used in which only a portion of thefibers are heat settable. This will not, of course, provide the optimumelastic properties. Moreover, not only highly drafted webs and cardedwebs of staple length fibers may be used for the base but also garnetedand air laid webs of such fibers as well as directly laid alined webs ofmonofilament. It has been noted, however, that when webs such as cardedwebs are used for the base web in which an important proportion of thefibers are randomly oriented, those fibers not alined with the machinedirection appear to interfere with the loop production by the gatheringblade and the ultimate stretch characteristics. The most regularformation of loops and optimum elastic and stretch in the formed fabrichas been produced with those base webs having the highest proportion offibers alined with the machine direction as, for example, the highlydrafted webs made with the apparatus illustrated in FIG. 4.

The present invention may be more completely understood from thefollowing examples, which are illustrative of the invention but are notintended as limiting the scope of the invention. The method andapparatus of FIG. 4 was employed for forming the wrap material for theproducts described in the ensuing examples. The adhesive used as aplastisol formulation including, by weight: Geon 135" polyvinyl chlorideresin (manufactured by B.F. Goodrich, Akron, Oh. about 60 parts per 100parts resin of GP-261" dioctyl phthalate plasticizer (B.F. Goodrich),about 2.5 parts per 100 parts resin of CAB- O-SlL" pyrogenic silica(Cabot Corporation, Boston, Massachusetts) and a sufficient amount ofmineral spirits to bring the viscosity into the desired range (generallyfrom about 3 to 5 percent by weight, based on the total weight of theother components for a viscosity range of 3,500 4,000 cps). Theviscosities were measured with a Brookfield viscometer using a No. 4spindle and operating at rpm. The polyester used in the Examples wasFortrel Type 400 stable fibers, com mercially available from CelaneseFibers Marketing Company, Charlotte, NC. The approximate tenacity ofthese fibers is 4.8 g.p.d. with elongation at break falling in the 45-55percent range. Other physical properties include: loop tenacity (g.p.d.)4.4, initial modulus (g.p.d.) -40-45, yield stress (g.p.d.) 1.0, yieldstrain 3.7 percent, specific gravity 1.38 and melting point 500 F.

EXAMPLE 1 The base web was made from polyester fiber having a denier ofabout 2.25 and an average fiber length of ZB-inches. The polyvinylchloride plastisol, having a viscosity of from 3,700 to 4,000centipoises, was applied in diagonal lines one fourth inches apart inboth directions to form a diamond pattern. Rotogravure printing wasemployed and the intaglio roll had adhesive cells or lines 0.006 inchesdeep and 0.028 inches wide. The weight of the base web was about 12.8grams/sq. yd., with equal weights of fiber and adhesive being included.

The preheat drum 39 in the first stage of forming the web was maintainedat about 300 F. and operated at a surface speed of 65 ft./min. The baseweb 24 was thus carried to the heating drum 37 at a surface speed of 65ft../min.

The gathering blade 48 was positioned at an angle of of 54 andmaintained against the drum with a pressure of 27 p.s.i. The drum (9inches in diameter) was internally heated and maintained at atemperature of about 260 F.

The take away speed was 8 ft./min. to provide a take away ratio (i.e.surface speed around drum/take away speed) of 8.125. The resultantproduct weighed about 104 g/yd. This material then opened between twonips, the first traveling one sixth the speed of the second, and thenallowed to relax. This final product, which weighed 32 g/ydF, was usedas a pad wrap.

EXAMPLE ll Example 1 was repeated, except that the blade angle wasvaried between 17 and 74 (17, 34, 37, 45, 54, and 74 being specificallyused), and the weight of the base web was about 13 grams/sq.yd., withequal weights of fiber and adhesive being included.

Elastic nonwoven material capable of being stretched up to about twiceits opened machine direction length with a recoverability of from 80percent to 100 percent was obtained when the blade angle was betweenabout 20 and 54 (i.e. optimum stretch was not obtained with angles of 17and 74).

EXAMPLE Ill The base web was made from polyester fiber having a denierof 2.25 and an average fiber length of 3 inches. The polyvinyl chlorideplastisol having a viscosity of about 3,800 centipoise was applied indiagonal lines one quarter inches apart in both directions to form adiamond pattern. The intaglio roll used was the same as in Example I.The base web, which weighed 12.5 grams/yd. was cured on the preheat drum39 at 290 F. at a surface speed of 5 8 fpm. It was then carried to theheating drum 37. The gathering blade 48 was positioned at an angle of 74and maintained with a pressure of 27 p.s.i. The drum 37 was heated to atemperature of 270 F. The take away was run at 40 ft..min. (i.e., 1.45to 1 ratio). The resultant product weighed 18.1 g/yd.

As has been thus seen from the preceding Examples, elastic, high-loftnonwoven wraps can be made in accordance with the present invention bycarefully controlling certain process parameters. Initially, the edgeangle must be kept within certain critical ranges, depending upon theother parameters involved such as, for example, type of adhesive patternand fiber stifiness. Thus, while angles of from about 20 to about 120could be employed, the critical range narrows when fiber stiffness, typeof adhesive and the adhesive pattern are known. For example, with 2.25denier polyester, a polyvinyl chloride plastisol and a diamond pattern,a range of from about 20 to 54 should be employed.

The take away speed of the fabric from the blade edge is also important.With the blade 48 having an edge angle within the preferred range, andassuming the take away surface is cooled to substantially an ambienttemperature, e.g. 75 F. to F., the normal ratio of the surface speed ofthe heating drum 37 to the take away speed should be maintained in therange of from about 5:1 to about 10: l with a ratio of 7 to 8:1 beingpreferred. By increasing the ratio above 10: 1, by slowing down thefabric take away speed, more adhesive consolidation has been obtainedand the mass of the fiber loops is made somewhat more dense, so that afabric with a higher weight has been produced; but the adhesive linesbecome more strongly bonded together so subsequent drawing cannot openthe adhesive. By increasing the fabric take away speed, such that thefabric is not allowed to gather at the blade edge, the fabric will bedrawn or extended while the adhesive layer is still in a plasticcondition, thereby opening the adhesive layer, but not allowingsufficient residence time for the fibers to become as well heat set.Such webs while not as elastic still retain the properties of rapidpassage of exudate and no strikeback. (See Example III).

Further parameters that affect adhesive consolidation fiber looping atthe blade edge and the stretchability and elasticity characteristics ofthe elastic nonwoven fabric are the adhesive pattern applied to thefibers in the formation of the base web, the adhesive weight as apercentage of the weight of the web, and the area of the web covered bythe adhesive pattern. The adhesive was applied in the preparation ofExamples 1 AND 11 in the form of diagonal lines, criss-crossed, toprovide an open diamond pattern with the size of the opening in thediamond in the machine direction less than the lengths of the fibersused for the base webs. Thus, where Fortrel" T-400 polyester was used,with fiber lengths of from 2% to 3 inches, a V4 inch diamond patternapplying adhesive to 20 percent to 25 percent of the total web surfacewas found effective. The transverse adhesive lines, when consolidated bythe action of the gathering blade, are moved into proximity or abutmentwith each other but are only minimally bonded together. Thus, when theclosed form of the elastic nonwoven is opened, the original pattern willreappear but will be foreshortened (i.e. the machine direction distanceof the pattern will be less).

In the application of the adhesive to the base web, it has been observedthat by increasing the adhesive viscosity a sharp, distinct printedpattern will be obtained such that the fibers are securely attached tothe adhesive at distinct spaced points and are not embedded in adhesivethroughout their length. It is desired to have spaced points of fiberadhesive attachment so that fiber loops will be distinctly andseparately formed at the gathering blade so as to extend outwardly fromthe bonding adhesive layer. Fiber sizes over the entire prepared rangeof 1.5 to 3.0 denier have been successfully utilized in the base webwith a Mr inch diamond pattern of adhesive. With the light weight websof polyester used in the Examples, the ratio of fiber to adhesive wasapproximately 1: 1. It has been found that the degree of adhesive-fiberattachment in the base web is affected when the fiber to adhesive ratiowith such type fibers is increased above about 2521, so that the fiberloops do not form properly at the blade nor do the fibers havesufficient attachment to the adhesive layer in the finished fabric. Onthe other hand, increasing the relative amount of adhesive in the baseweb tends to produce a thicker adhesive layer in the finished materialand more secure fiber attachment, but the adhesive lines tend todisperse so that the pattern becomes less open affecting the height ofthe loops, which is undesirable. The fiber-adhesive ratio will bedifferent, however, for base webs of yarns and threads where it appearsthat less amounts of adhesive, relatively speaking, will provideadequate attachment of the loops to the adhesive backing layer. For thepurposes of the present invention, the aforementioned parameters are allpreferably selected to provide a final gathered web of about to about 40grams/yd.

It is also recognized that to produce a material in accordance with theinvention, the elements should be sufficiently flexible to allow theloops to form under the action of the adhesive consolidating andgathering blade. Thus, neither stiff strands which do not loop-under theaction of the gathering blade, nor multiple strand yarns in which thelay of the strands opposes the tendency of the loops being formed toassume their equilibrium position under the action of the blade,

will satisfactorily serve as elements of the base web when it is.

desired to produce a fabric fully in accordance with the invention.

As shown in FIG. 4, the fabric is carried along the take-away surface 51by the action of the conveyor 62. Since the adhesive backing is hot andtacky as the fabric flows onto the takeaway surface 51 which ismaintained substantially at ambient temperatures, that surface may betreated with a nonstick or release coating to insure that the fabric maybe drawn smoothly along the surface.

To cool the belt of the conveyor 52 and prevent it from becomingoverheated from the hot adhesive back of the fabric 50, streams of airmay be blown against the underside of the belt from suitably placed airnozzles 60. This will also serve to cool the fabric 50, although it maybe necessary or desirable to pass the fabric through a cooling stationor zone to cool the adhesive and thermoplastic fibers clearly belowtheir softening temperatures or to eliminate tackiness of the adhesive.

The improved wrap material provided by this invention provides rapidpassage of the relatively viscous menstrual exudate into the absorbentcore material, and yet the exudate does not strike back through the wrapmaterial. In fact, the wrap material is essentially non-wettable byexudate. It is believed that these results are due to the uniquecombination of characteristics of the wrap material, particularly itsbulk or loft and its hydrophobic nature. To demonstrate thesignificantly improved results obtained with sanitary napkins embodyingthis invention, a number of napkins of the type illustrated in FIGS.l-3, made with a high-loft wrap material of the type described inExample III, were subjected to comparative tests with conventionalcommercial Kotex and Modess napkins. In these tests, three differentsamples of each of the three napkin types were tested by placing on eachnapkin 3 ml. of liquid having a viscosity of 25 cps. at a shear of 23sec. -1 on a Brookfield viscometer, and then measuring the time (inseconds) required for all the fluid to penetrate the wrap material ofeach pad. These tests were repeated using different test liquids havingthe same viscosity as the liquid described above, this time using onlyone sample of each of the three napkin types for each liquid sample. Thedata recorded in the foregoing tests was as follows:

a 6.9 sec. 7.9 sec. 4.2 sec. Pad No. 3 7.1 sec. 6.6 sec. 4.5 sec.

7.1 sec. 6.8 sec. 4.3 sec. Average 16.1 sec. 13.45 sec. 10.65 sec.Liquid No. 2

Average 16.1 sec. 13.45 sec. 10.65 sec. Liquid No. 3

Average 6.43 sec. 6.55 sec. 4.75 sec.

As can be seen from the foregoing data, the napkins of the presentinvention consistently provided the more rapid absorptioncharacteristics. Furthermore, it was observed that there wassubstantially no wetting of the wrap material in the napkins of theinvention.

1 claim as my invention:

1. A sanitary napkin comprising the combination of a central pad ofabsorbent material and an elastic wrap disposed around said central padof absorbent material and comprising an elastic high-loft, nonwovenfabric having a discontinuous backing layer of flexible adhesivedisposed adjacent said central pad and a multiplicity of heat settablehydrophobic fibers individually looped outwardly from said backing layerand heat set in the looped form with the ends of each loop embedded insaid backing layer, said wrap being elastic to provide conformabilityenabling more unifonn contact with said central pad.

2. A sanitary napkin as set forth in claim 1 wherein thefiber-to-adhesive ratio in said high-loft wrap material is from about1:1 to about 2.5:1.

3. A sanitary napkin as set forth in claim 1 wherein said high-loft wrapmaterial weighs from about 15 to about 40 grams/yd.

4. A sanitary napkin as set forth in claim 1 wherein the fibers in saidhigh-loft wrap material have a denier of from about 1.5 to about 3.0.

5. An improved sanitary napkin as set forth in claim I wherein saidbacking layer of said napkin fabric comprises a series of interconnectedhexagons of adhesive.

6. An improved sanitary napkin as set forth in claim 5 wherein thespacing of said points varies regularly for said fibers throughout thefabric so that said loops vary in height regularly throughout thefabric.

7. An improved sanitary napkin as set forth in claim 1 wherein saidfiber loops in said napkin fabric lie in planes extending in the crossdirection of the fabric.

8. An improved sanitary napkin as set forth in claim 1 wherein saidnapkin fabric comprises a discontinuous, flexible backing of adhesiveand a multiplicity of heat-set fibers each embedded at spacedlongitudinal points in said backing layer and with the fiber portionsbetween said points being looped outwardly from said backing layer.

9. In a sanitary napkin having a central pad of absorbent material, animproved elastic wrap disposed around said central pad and extendingoutwardly beyond the opposite ends thereof for providing fastening tabs,said wrap comprising an elastic high-loft, nonwoven fabric having adiscontinuous backing layer of flexible adhesive disposed adjacent saidcentral pad and a multiplicity of heat settable hydrophobic fibersindividually looped outward1y from said backing layer and heat set inthe looped form with the ends of each loop embedded in said backinglayer, said loops extending over the open spaces in said discontinuousbacking layer, said open spaces facilitating the passing of fluidsthrough said wrap to said central pad of absorbent material, saidelastic wrap enabling more uniform contact with said central pad.

2. A sanitary napkin as set forth in claim 1 wherein thefiber-to-adhesive ratio in said high-loft wrap material is from about1:1 to about 2.5:1.
 3. A sanitary napkin as set forth in claim 1 whereinsaid high-loft wrap material weighs from about 15 to about 40 grams/yd.24. A sanitary napkin as set forth in claim 1 wherein the fibers in saidhigh-loft wrap material have a denier of from about 1.5 to about 3.0. 5.An improved sanitary napkin as set forth in claim 1 wherein said backinglayer of said napkin fabric comprises a series of interconnectedhexagons of adhesive.
 6. An improved sanitary napkin as set forth inclaim 5 wherein the spacing of said points varies regularly for saidfibers throughout the fabric so that said loops vary in height regularlythroughout the fabric.
 7. An improved sanitary napkin as set forth inclaim 1 wherein said fiber loops in said napkin fabric lie in planesextending in the cross direction of the fabric.
 8. An improved sanitarynapkin as set forth in claim 1 wherein said napkin fabric comprises adiscontinuous, flexible backing of adhesive and a multiplicity ofheat-set fibers each embedded at spaced longitudinal points in saidbacking layer and with the fiber portions between said points beinglooped outwardly from said backing layer.
 9. In a sanitary napkin havinga central pad of absorbent material, an improved elastic wrap disposedaround said central pad and extending outwardly beyond the opposite endsthereof for providing fastening tabs, said wrap comprising an elastichigh-loft, nonwoven fabric having a discontinuous backing layer offlexible adhesive disposed adjacent said central pad and a multiplicityof heat settable hydrophobic fibers individually looped outwardly fromsaid backing layer and heat set in the looped form with the ends of eachloop embedded in said backing layer, said loops extending over the openspaces in said discontinuous backing layer, said open spacesfacilitating the passing of fluids through said wrap to said central padof absorbent matErial, said elastic wrap enabling more uniform contactwith said central pad.